#play-chess-hover {
    width: 40px;
    height: 40px;
    position: absolute;
    font-size: 16px;
    z-index: 999;
    pointer-events: none;
    display: none;
}

#play-chess-hover {
    opacity: 0; /* 初始透明度 */
    transition: opacity 0.5s ease-in-out; /* 过渡效果 */
    border-image-source: radial-gradient(55% 55%, transparent 0px, transparent 100%, white 100%);
    border-image-slice: 1;
    border-width: 1px;
    border-style: solid;
}

#play-chess-hover.show {
    display: block;
    opacity: 1; /* 显示时的透明度 */
    animation: flash 2s infinite; /* 无限循环闪烁动画 */
}

@keyframes flash {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}
